Variable resister.



J. H. HODDE.

. VARIABLE RESISTER.

APPLICATION FILED MAY 3, 1915. 1,177,702.

I 17 11 12 g Patented Apr, 4,1915 10 El::; Lg H] Jql 14 I a 46 20 f 1 u 'iiiii 43 9 mnnnl lmllll f "I" gum! @l I I' WW 14 -;mm!mnm l%' 15 1 UNITED STATES PATENT OFFICE.

JACOB H. HODDE, 0F SPRINGFIELD, ILLINOIS, ASSIGNOR TO SANGAMO ELECTRIC COMPANY, OF SPRINGFIELD, ILLINOIS, A CORPORATION OF ILLINOIS.

VARIABLE RESISTER.

Specification of Letters Patent.

Patented Apr. 4, 1916.

1 0 all whom it may concern Be it known that I, JACOB H. Home, a citizen of the United States, and a resident of Springfield, in the county of Sangamon and State of Illinois, have invented certain new and useful Improvements in Variable Resisters, of which the following is a specification, reference being had to the accompanying drawings.

My invention relates to electr1c1ty meters and analogous devices, and has more particularly to do with a variable reslstance element designed to be employed in association with a reversible meter, or analogous device, to automatically vary the rate of the meter when operated by current flowing in one direction through it as compared with its rate when operated by oppositely-flowing current. An apparatus of this description is shown and described in my pending application, Serial No. 729,010, filed November 1, 1912.

The variable resister described in my said application comprises a mercury chamber having contact plates at opposite sides thereof forming terminal connections. swinging conductor, in the form of a vane or bar of conducting material, such as copper, is mounted in the mercury chamber so as to be immersed in the mercury therein contained, the mercury chamber being so disposed with reference to the poles of a permanent magnet that the flow of current through the mercury chamber, reacting with the magnetic field, will cause the vane to swing or partially rotate about its axis. As the vane is a better conductor than the mercury, when it is in line, or substantially in line, with the mercury chamber terminals, a path of least resistance is presented to the flow of current through the mercury chamber. W'hen, however, the vane or bar swings out of such line, the resistance will be increased to an extent corresponding with the extent of movement of the bar, and would reach the maximum if the bar should occupy a position perpendicular to a line connecting the mercury chamber terminals. To prevent the bar or vane from completely rotating, suitable stops are provided to intercept it at proper points so as to confine its movement within the desired range. One of such stops is so placed that with current flowing in one direction the vane will be in line, or approximately in line, with the mercury chamber terminals, while the other stop is placed so as to permit the vane to swing through an arc of about thirty degrees under the influence of current flowing in the opposite direction.

My present invention has for its object to improve the construction of the resister above described by providing convenient means for varying the range of movement of the swinging element or vane without opening up the mercury receptacle. Obviously, this construction must be such as to prevent the escape of mercury from the mercury chamber. I accomplish this object as illustrated in the drawings and as hereinafter described.

That which I believe to be new is set forth in the claims.

In the accompanying drawings, Figure 1 is an edge view of the variable resister, showing, also, the lower ends of the poles of the permanent magnet with which it is associated; Fig. 2 is a plan view of the resister, the cover-plate being removed, showing one form of adjustable stop; Fig. 3 is a detail, partly in section, showing the construction of the stop; Fig. 4 is a bottom view of the resister shown in the preceding figures; Fig. 5 is an edge view showing a modified form of resister, in which the mercury chamber is elongated instead of circular in shape; Fig. 6 is a plan view of the resister shown in Fig. 5, the cover-plate being removed; and Fig. 7 is a bottom view of the construction shown in Figs. 5 and 6.

Referring to the drawings, 8 indicates a receptacle formed of suitable non-conducting material, which contains a mercury chamber 9. It is provided with a cover-plate 10 having a central boss 11 provided with a bearing 12 for the upper end of the vane spindle hereinafter described.

13-14 indicate terminals which extend into opposite sides of the mercury chamber and serve as a means for making electrical connection therewith.

15 indicates a copper bar or vane, which is provided with a spindle or shaft 16, the upper end of which is fitted in the bearing 12, its lower end being fitted in a suitable bearing provided in the receptacle 8.

1718 indicate the poles of a permanent magnet, which overlie the cover-plate 10 in such position that the mercury chamber 9 lies in the magnetic field of such magnet. Obviously, according to well understood principles, when current is caused to flow from one of the terminals, as 13, to the other terminal, its reaction with the magnetic field will cause the vane 15 to swing in one direction; Whereas, i'f'current flows in the opposite direction, as from the terminal 14 to the terminal 13, the v ane will swing in the opposite direction. When the vane 15 is in line with the terminals 13-14, or substantially so, as its resistance is less than that of the mercury in the mercury chamber, less resistance will be presented to the flow of current through the mercury chamber 9 than is the case when the vane 15 is swung outof line with said terminals, as in that case the current must flow for a greater or less distance through the mercury depending upon the position of the vane. It follows that when the vane is nearest a position in line with the terminals, the meter with which the resister is connected will operate at a faster rate than when said vane is swung to a position' in which it lies at a greater angle to such line. One of these conditions obtains when the current flows in one direction through the resister and the other when the current flows in the opposite directicn.

In order to limit the range of movement of the vane 15, in the construction shown in Fig. 2 I provide a fixed stop 19 placed about thirty or forty degrees from a line connecting the terminals 1814 and in position to intercept the vane as it swings. This stop determines the position of maximum resistance. I also provide an adjustable stop 20 which, in the construction shown in Figs. 1 to 4, is carried eccentrically by a rotary sup port, preferably in the form of a disk 21, said disk being secured to the upper end of a screw 22 extending through the bottom of the receptacle 8, as shown iii-Fig. 3. The stem of said screw is provided with a bushing 23 which is fitted in a suitable bearing provided in the bottom of the receptacle 8. A washer 24 overlies the lower end of the bushing 23 and is countersunk to receive the head of the screw 22, as shown. It will be apparent that by the use of a screwdriver the disk 21 may be rotated, thereby adjusting the position of the stop 20 with reference to the vane 15, and consequently varying the minimum resistance position of said vane. If the stop 20 be swung to the position shown in dotted lines in Fig. 2, the minimum resistance position of the vane 15 will be as shown in dotted lines in said figure, while its maximum resistance position will be determined by the stationary stop 19. Under these conditions, the range of movement of the vane 15 would be quite limited, but with the stop 20 in the position shown in full lines in Fig. 2 the vane would have a range of movement of approximately thirty degrees, which I have found by experiment to be the range within which the maximum effect is secured.

In the construction shown in Figs. 5, 6

' and 7, I employ a mercury receptacle 25,

which is segmental in shape, one of the side margins of the mercury receptacle, as 26-, forming one of the permanent stops to limit the range or movement of the vane 27. In this case the vane is provided with a laterally-projecting finger 28 adjacent to its pivot 29, which finger is adapted to engage a stop 30 carried eccentrically by a rotary support, such as a disk 31. This disk is connected by a pivot (not shown) with an arm or pointer 32 fitted upon the bottom of the mercury receptacle and adapted to engage stops 33.3 l suitably placed to limit its movement. By this construction the stop 30 may be adjusted to any desired position by simply swinging the pointer 32, and by marking a scale on the bottom of the mercury receptacle, the position of the stop 30 will be indicated at all times so that the position of the pointer will indicate at all times the range of movement of the vane.

In the construction shown in Figs. 1 to 4:

this could also be indicated by appropriately marking the washer 24 and the bottom of the mercury receptacle, as indicated by the black arrows on Fig. 42.

By the construction described I provide a very simple, convenient and efiective means of adjusting the range of movement of the vane without opening up the mercury chamber and without impairing the tightness of the mercury chamber as a mercury container.

The resister may be connected either in series with the armature chamber of the meter across the shunt, or in parallel with the armature chamber, both of which connections are illustrated in my pending application hereinbefore referred to. In the foregoing description of the operation of the resister it is assumed that the resister is connected up in the first of these ways. When connected in parallel, the resister operates to reduce the rate of the meter when the vane is in line with the terminals of its mercury chamber, instead of to increase the rate of the meter under such conditions, as is the case when the resister is connected in series with the armature chamber.

That which I claim as my invention, and desire to secure by Letters Patent, is,

1. A variable resister, comprising a conductor composed of a body of mercury, a conducting element of different conductivity, the latter element being movable to vary the proportionate parts of such elements which are interposed in the path of the current, ad-

justable means for controlling the extent of movement of said movable element, and a magnet associated with said conductor for controlling the movement of said movable element.

2. A variable resister, comprising a body of mercury, a pivotally-mounted non-circular conducting element of different conductivity, said elements being associated to jointly form a path for the current the resistance of which may be varied by the rotation of said pivoted element, adjustable means for varying the range of movement of said pivoted element, and a magnet associated with said conductor for controlling the movement of said pivoted element.

3. A variable resister, comprising a mercury chamber, a pivotally-mounted non-circular conducting element in said mercury chamber, contacts at opposite sides of said mercury chamber, and adjustable means in said mercury chamber for varying the range of movement of said pivoted element.

4. A variable resister, comprising a mercury chamber, a pivotally-mounted non-circular conducting element in said mercury chamber, contacts at opposite sides of said mercury chamber, an ad ustable stop in said mercury chamber for varying the range of movement of said pivoted element, and

means whereby said stop may be adjusted from without said mercury chamber.

5. A variable resister, comprising a mercury chamber, a conducting vane pivotally mounted in said chamber, contacts at opposite sidesof said chamber, an adjustable stop in said chamber adapted to limit the movement of said vane, and means for adjusting the position of said stop from without the mercury chamber.

6. A variable risister, comprising a mercury chamber, a conducting vane pivotally mounted in said chamber, contacts at opposite sides of said chamber, a pivoted support fitted in said chamber, a stop carried eccentrically by said support, and means whereby said support may be rotated from without the mercury chamber.

7. A varlable resister, comprising a mercury chamber, a swinging vane in said chamber, contacts at opposite sides of said chamber, an adjustable stop adapted to be adjusted from without said chamber for varying the range of movement of said vane, and means outside of said mercury chamber for indicating the position of said stop.

JACOB H. HODDE.

Witnesses:

ROBERT C. LANPHIER, W. P. SOUTHWICK. 

